Before you head home for what is supposed to be a gorgeous weekend of sun and leisure, the fine folks of Critical Mass will be in full effect during the evening commute. Just like every last Friday of the month, cyclists will gather at Justin Hermann Plaza at the foot of Market Street at 6 p.m., then bloom throughout the streets of SF with much fanfare. And, due of the large number of bicyclists, traffic (mainly in the downtown area) will be wonky. Please adjust your route home accordingly. To learn more about riding your purple Schwinn around town, visit SFBike.org.